bbbe67bf7c
* Vendors packages * Adds a Makefile that uses docker to build a static binary against musl using alpine linux. Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>
95 lines
2.7 KiB
Markdown
95 lines
2.7 KiB
Markdown
# fastuuid
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--
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import "github.com/rogpeppe/fastuuid"
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Package fastuuid provides fast UUID generation of 192 bit universally unique
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identifiers.
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It also provides simple support for 128-bit RFC-4122 V4 UUID strings.
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Note that the generated UUIDs are not unguessable - each UUID generated from a
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Generator is adjacent to the previously generated UUID.
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By way of comparison with two other popular UUID-generation packages,
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github.com/satori/go.uuid and github.com/google/uuid, here are some benchmarks:
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BenchmarkNext-4 128272185 9.20 ns/op
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BenchmarkHex128-4 14323180 76.4 ns/op
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BenchmarkContended-4 45741997 26.4 ns/op
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BenchmarkSatoriNext-4 1231281 967 ns/op
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BenchmarkSatoriHex128-4 1000000 1041 ns/op
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BenchmarkSatoriContended-4 1765520 666 ns/op
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BenchmarkGoogleNext-4 1256250 958 ns/op
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BenchmarkGoogleHex128-4 1000000 1044 ns/op
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BenchmarkGoogleContended-4 1746570 690 ns/op
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## Usage
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#### func Hex128
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```go
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func Hex128(uuid [24]byte) string
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```
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Hex128 returns an RFC4122 V4 representation of the first 128 bits of the given
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UUID. For example:
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f81d4fae-7dec-41d0-8765-00a0c91e6bf6.
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Note: before encoding, it swaps bytes 6 and 9 so that all the varying bits of
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the UUID as returned from Generator.Next are reflected in the Hex128
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representation.
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If you want unpredictable UUIDs, you might want to consider hashing the uuid
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(using SHA256, for example) before passing it to Hex128.
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#### func ValidHex128
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```go
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func ValidHex128(id string) bool
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```
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ValidHex128 reports whether id is a valid UUID as returned by Hex128 and various
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other UUID packages, such as github.com/satori/go.uuid's NewV4 function.
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Note that it does not allow upper case hex.
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#### type Generator
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```go
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type Generator struct {
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}
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```
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Generator represents a UUID generator that generates UUIDs in sequence from a
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random starting point.
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#### func MustNewGenerator
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```go
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func MustNewGenerator() *Generator
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```
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MustNewGenerator is like NewGenerator but panics on failure.
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#### func NewGenerator
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```go
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func NewGenerator() (*Generator, error)
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```
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NewGenerator returns a new Generator. It can fail if the crypto/rand read fails.
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#### func (*Generator) Hex128
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```go
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func (g *Generator) Hex128() string
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```
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Hex128 is a convenience method that returns Hex128(g.Next()).
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#### func (*Generator) Next
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```go
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func (g *Generator) Next() [24]byte
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```
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Next returns the next UUID from the generator. Only the first 8 bytes can differ
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from the previous UUID, so taking a slice of the first 16 bytes is sufficient to
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provide a somewhat less secure 128 bit UUID.
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It is OK to call this method concurrently.
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